Nr mobility - security considerations for l1/l2 mobility switching of an spcell

Abstract

A wireless transmit/receive unit (WTRU) may be configured to process first downlink data from a source cell using a first security context. The WTRU may receive, from the source cell, configuration information indicating one or more candidate cells for Layer 1 or Layer 2 (L1/L2) triggered mobility (LTM). The WTRU may receive, from the source cell, a LTM indication to perform a handover (HO) to a candidate cell among the one or more candidate cells. The WTRU may determine a second security context associated with the candidate cell. The WTRU may process second downlink data based on the first security context. The WTRU may process third downlink data from the candidate cell using the second security context upon a determination that one or more of the conditions are met.

What is claimed is: 
     
         1 . A wireless transmit receive unit (WTRU) comprising:
 a processor configured to:
 process first downlink data from a source cell using a first security context; 
 receive, from the source cell, configuration information indicating one or more candidate cells for Layer 1 or Layer 2 (L1/L2) triggered mobility (LTM); 
 receive, from the source cell, an LTM indication to perform a handover (HO) to a candidate cell among the one or more candidate cells; 
 determine a second security context associated with the candidate cell; process second downlink data using the first security context; and 
 process third downlink data from the candidate cell using the second security context upon a determination that one or more conditions are met, wherein the one or more conditions comprise:
 a determination that a certain time has elapsed from the reception of the LTM indication to perform the HO; 
 a determination that an integrity verification with one or more old security keys has failed; or 
 a determination that an end marker packet is received. 
 
   
     
     
         2 . The WTRU of  claim 1 , wherein the end marker packet comprises one or more of a dummy radio resource control (RRC) message, a packet data convergence protocol (PDCP) control protocol data unit (PDU) that comprises an indication to use the second security context, or a field in a PDCP data PDU header that comprises an indication to use the second security context. 
     
     
         3 . The WTRU of  claim 1 , wherein the processor is configured to:
 prior to receiving the LTM indication to perform the HO, transmit first uplink data to the source cell using the first security context;   after receiving the LTM indication to perform the HO, transmit second uplink data to the candidate cell that is encrypted using the second security context; and   after the determination that at least one of the one or more conditions are met, transmit third uplink data that is encrypted using the second security context.   
     
     
         4 . The WTRU of  claim 1 , wherein the one or more old security keys are associated with the first security context. 
     
     
         5 . The WTRU of  claim 1 , wherein the processor is configured to use the second security context, and refrain from using the first security context, upon the determination that the at least one of the one or more conditions are met. 
     
     
         6 . The WTRU of  claim 1 , wherein the first security context comprises one or more security keys. 
     
     
         7 . The WTRU of  claim 1 , wherein determining the second security context comprises deriving a new key for the candidate cell (KgNB) and calculating, using a physical cell identification (PCI) and a frequency of a primary cell (PCell), one or more integrity protection keys and decryption keys. 
     
     
         8 . The WTRU of  claim 7 , wherein processing the third downlink data comprises performing integrity verification and decryption using the one or more integrity protection keys and decryption keys associated with the second security context. 
     
     
         9 . The WTRU of  claim 1 , wherein the LTM indication to perform the HO indicates that a special cell (SpCell) associated with the WTRU is to be changed. 
     
     
         10 . The WTRU of  claim 1 , wherein the processor is further configured to:
 refrain from performing re-establishment of radio resource control (RRC), packet data convergence protocol (PDCP), and radio link control (RLC) entities; and   refrain from resetting medium access control (MAC) and physical layer entities.   
     
     
         11 . A method performed in a wireless transmit receive unit (WTRU), the method comprising:
 processing first downlink data from a source cell using a first security context; receiving, from the source cell, configuration information indicating one or more candidate cells for Layer 1 or Layer 2 (L1/L2) triggered mobility (LTM);   receiving, from the source cell, an LTM indication to perform a handover (HO) to a candidate cell among the one or more candidate cells;   determining a second security context associated with the candidate cell; processing second downlink data using the first security context; and   processing third downlink data from the candidate cell using the second security context upon a determination that one or more conditions are met, wherein the one or more conditions comprise:
 a determination that a certain time has elapsed from the reception of the LTM indication to perform the HO; 
 a determination that an integrity verification with one or more old security keys has failed; or 
 a determination that an end marker packet is received. 
   
     
     
         12 . The method of  claim 11 , wherein the end marker packet comprises one or more of a dummy radio resource control (RRC) message, a packet data convergence protocol (PDCP) control protocol data unit (PDU) that comprises an indication to use the second security context, or a field in a PDCP data PDU header that comprises an indication to use the second security context. 
     
     
         13 . The method of  claim 11 , further comprising:
 prior to receiving the LTM indication to perform the HO, transmitting first uplink data to the source cell using the first security context;   after receiving the LTM indication to perform the HO, transmitting second uplink data to the candidate cell that is encrypted using the second security context; and   after the determination that at least one of the one or more conditions are met, transmitting third uplink data that is encrypted using the second security context.   
     
     
         14 . The method of  claim 11 , wherein the one or more old security keys are associated with the first security context. 
     
     
         15 . The method of  claim 11 , further comprising using the second security context, and refraining from using the first security context, upon the determination that the at least one of the one or more conditions are met. 
     
     
         16 . The method of  claim 11 , wherein the first security context comprises one or more security keys. 
     
     
         17 . The method of  claim 11 , wherein determining the second security context comprises deriving a new key for the candidate cell (KgNB) and calculating, using a physical cell identification (PCI) and a frequency of a primary cell (PCell), one or more integrity protection keys and decryption keys using the candidate cell. 
     
     
         18 . The method of  claim 17 , wherein processing the third downlink data comprises performing integrity verification and decryption using the one or more integrity protection keys and decryption keys associated with the second security context. 
     
     
         19 . The method of  claim 11 , wherein the LTM indication to perform the HO indicates that a special cell (SpCell) associated with the WTRU is to be changed. 
     
     
         20 . The method of  claim 11 , further comprising:
 refraining from performing re-establishment of radio resource control (RRC), packet data convergence protocol (PDCP), and radio link control (RLC) entities; and   refraining from resetting medium access control (MAC) and physical layer entities.